An electrostatic discharge protection device including a silicon controlled rectifier. In one example, the silicon controlled rectifier includes a first n-type region located in a semiconductor substrate. The silicon controlled rectifier also includes a first p-type region located adjacent the first n-type region in the semiconductor substrate. The silicon controlled rectifier further includes an n-type contact region and a p-type contact region located in the first n-type region. The silicon controlled rectifier also includes an n-type contact region and a p-type contact region located in the first p-type region. The silicon controlled rectifier further includes a blocking region having a higher resistivity than the first p-type region. The blocking region is located between the n-type contact region and the p-type contact region in the first p-type region for reducing a trigger voltage of the silicon controlled rectifier.
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1. An electrostatic discharge protection device comprising a silicon controlled rectifier, the silicon controlled rectifier comprising: a first region having a first conductivity type located in a semiconductor substrate; a second region having a second conductivity type located adjacent the first region having the first conductivity type in the semiconductor substrate; a third region having the first conductivity type located adjacent the second region having the second conductivity type in the semiconductor substrate, wherein the second region is between the first region and the third region; a first contact region of the first conductivity type and a second contact region of the second conductivity type located in the first region having the first conductivity type; a third contact region of the first conductivity type and a fourth contact region of the second conductivity type located in the second region having the second conductivity type; a fifth contact region of the first conductivity type and a sixth contact region of the second conductivity type located in the third region having the first conductivity type; and a blocking region having a higher resistivity than the region having the second conductivity type, wherein the blocking region is located between the third contact region of the first conductivity type and the fourth contact region of the second conductivity type in the second region having the second conductivity type, for reducing a trigger voltage of the silicon controlled rectifier.
An electrostatic discharge (ESD) protection device contains a silicon controlled rectifier (SCR) built on a semiconductor substrate. The SCR has alternating regions of different conductivity types (N-type and P-type): a first region (N or P), a second region (opposite type to the first), and a third region (same type as the first). Contact regions are present in each of these regions to allow electrical connections. Crucially, a high-resistivity "blocking region" is placed within the second region (between two contact regions) to reduce the voltage needed to trigger the SCR, enhancing its ESD protection.
2. The electrostatic discharge protection device of claim 1 , wherein: the first contact region of the first conductivity type and the second contact region of the second conductivity type located in the first region having the first conductivity type are connected to a first node of the device, and the fifth contact region of the first conductivity type and the sixth contact region of the second conductivity type located in the third region having the first conductivity type are also connected to said first node.
The ESD protection device as described containing the SCR is enhanced by connecting contact regions from the first and third regions (which have the same conductivity type) to a single node of the device, which effectively ties them together. Specifically, the first and second contact regions in the first region and the fifth and sixth contact regions in the third region are electrically connected to the same first node.
3. The electrostatic discharge protection device of claim 2 , wherein the first node comprises a power supply rail or I/O pad of the device.
In the ESD protection device where contact regions from the first and third regions are tied to a common node, this node serves as either a power supply rail or an input/output (I/O) pad on the device. This allows the ESD protection to be directly integrated with the power or signal lines it is intended to protect.
4. The electrostatic discharge protection device of claim 2 , wherein the third contact region of the first conductivity type and the fourth contact region of the second conductivity type located in the second region having the second conductivity type are connected to a second node of the device.
In the ESD protection device where contact regions from the first and third regions are tied to a common node, the third and fourth contact regions located in the second region (which has opposite conductivity to the first and third regions) are connected to a separate, second node on the device. This creates a distinct path for the ESD current to flow through the SCR.
5. The electrostatic discharge protection device of claim 4 , wherein the second node is a ground rail of the device.
Regarding the ESD protection device where the third and fourth contact regions in the second region are connected to a second node, this second node is connected to the ground rail of the device. This configuration directs the ESD event current to ground.
6. The electrostatic discharge protection device of claim 1 comprising a seventh contact region of the first conductivity type located in the second region having the second conductivity type, wherein the third contact region of the first conductivity type and the seventh contact region of the first conductivity type located in the second region having the second conductivity type form a bipolar transistor within the second region having the second conductivity type.
The ESD protection device described with a silicon controlled rectifier (SCR) has an additional, seventh contact region of the same conductivity type as the first and third regions (and opposite to the second region) located within the second region. The existing third contact region and this new seventh contact region together form a bipolar transistor within the second region, enabling faster switching.
7. The electrostatic discharge protection device of claim 6 further comprising a gate for applying a potential to a portion of the second region having the second conductivity type located in-between the third contact region of the first conductivity type and the seventh contact region of the first conductivity type.
The ESD protection device featuring a silicon controlled rectifier (SCR) with an internal bipolar transistor, further includes a gate. This gate applies a voltage to a specific area within the second region, situated between the third and seventh contact regions which together form the transistor.
8. The electrostatic discharge protection device of claim 7 , wherein the gate is connected to a slew rate detection circuit.
The ESD protection device with the gate in the second region (between the third and seventh contact regions) is further enhanced. The gate is connected to a slew rate detection circuit, enabling the SCR to react specifically to fast voltage changes indicative of an ESD event.
9. The electrostatic discharge protection device of claim 7 , wherein the gate is connected to a node of the device that is also connected to the third contact region and the fourth contact region in the second region.
In the ESD protection device employing a gate within the second region, it is connected to the same node that the third and fourth contact regions of the second region are connected. Thus, the gate potential tracks the voltage at that node.
10. The electrostatic discharge protection device of claim 1 comprising an underlying layer having the first conductivity type extending beneath the second region having the second conductivity type in the substrate for isolating the second region having the second conductivity type from an underlying region of the substrate.
The ESD protection device's silicon controlled rectifier (SCR) is built with an underlying layer of the same conductivity type as the first and third regions beneath the second region. This underlying layer isolates the second region from deeper parts of the substrate, improving device performance.
11. The electrostatic discharge protection device of claim 1 , wherein the blocking region is undoped or has a lower doping level than the second region having the second conductivity type.
In the electrostatic discharge protection device incorporating a silicon controlled rectifier (SCR), the blocking region, designed to reduce the trigger voltage, is either undoped (no intentional impurities added) or has a lower doping concentration than the surrounding second region.
12. The electrostatic discharge protection device of claim 1 , wherein a dimension W of the blocking region extending between the third contact region of the first conductivity type and the fourth contact region of the second conductivity type in the second region having the second conductivity type is in the range 1 μm≦W≦2 μm.
For the ESD protection device incorporating a silicon controlled rectifier (SCR), the width (W) of the blocking region, the region of higher resistivity, that is located between contact regions in the second region has a specific dimension, between 1 and 2 micrometers (1 μm ≤ W ≤ 2 μm).
13. The electrostatic discharge protection device of claim 10 , wherein the underlying layer having the first conductivity type further extends under a portion of the first region by a first overlap distance, wherein a resistance associated with the first region is based on the first overlap distance.
The ESD protection device's SCR has an underlying layer extending under the second region. This underlying layer also extends, by a first overlap distance, under a portion of the first region. The resistance of the first region is influenced by the length of this overlap.
14. The electrostatic discharge protection device of claim 13 , wherein the underlying layer having the first conductivity type further extends under a portion of the third region by a second overlap distance, wherein a resistance associated with the third region is based on the second overlap distance.
The ESD protection device described above uses an underlying layer extending under both the first and second regions. This underlying layer also overlaps under a portion of the third region. The length of this second overlap affects the resistance of the third region.
15. The electrostatic discharge protection device of claim 1 , wherein a first bipolar transistor is formed within the first region, a second bipolar transistor is formed within the second region, the first and second bipolar transistors have opposite conductivity types.
The ESD protection device containing the SCR has an additional feature; a first bipolar transistor is formed within the first region. A second bipolar transistor is formed within the second region. These two bipolar transistors have opposite conductivity types (one is NPN, the other is PNP).
16. The electrostatic discharge protection device of claim 15 , wherein a third bipolar transistor is formed by the sixth contact region, the third region, and the second region, the first and third bipolar transistors have same conductivity types.
The ESD protection device has the bipolar transistors, and a third bipolar transistor is formed by the sixth contact region, the third region, and the second region. The first and third bipolar transistors have the same conductivity types.
17. An electrostatic discharge protection circuit comprising a silicon controlled rectifier, the silicon controlled rectifier comprising: a first region having a first conductivity type located in a semiconductor substrate; a second region having a second conductivity type located adjacent the first region having the first conductivity type in the semiconductor substrate; a third region having the first conductivity type located adjacent the second region having the second conductivity type in the semiconductor substrate, wherein the second region is between the first region and the third region; a first contact region of the first conductivity type and a second contact region of the second conductivity type located in the first region having the first conductivity type; a third contact region of the first conductivity type and a fourth contact region of the second conductivity type located in the second region having the second conductivity type; a fifth contact region of the first conductivity type and a sixth contact region of the second conductivity type located in the third region having the first conductivity type; and a blocking region having a higher resistivity than the region having the second conductivity type, wherein the blocking region is located between the third contact region of the first conductivity type and the fourth contact region of the second conductivity type in the second region having the second conductivity type, for reducing a trigger voltage of the silicon controlled rectifier.
An electrostatic discharge (ESD) protection circuit contains a silicon controlled rectifier (SCR) built on a semiconductor substrate. The SCR has alternating regions of different conductivity types (N-type and P-type): a first region (N or P), a second region (opposite type to the first), and a third region (same type as the first). Contact regions are present in each of these regions to allow electrical connections. Crucially, a high-resistivity "blocking region" is placed within the second region (between two contact regions) to reduce the voltage needed to trigger the SCR, enhancing its ESD protection.
18. An integrated circuit comprising a silicon controlled rectifier, the silicon controlled rectifier comprising: a first region having a first conductivity type located in a semiconductor substrate; a second region having a second conductivity type located adjacent the first region having the first conductivity type in the semiconductor substrate; a third region having the first conductivity type located adjacent the second region having the second conductivity type in the semiconductor substrate, wherein the second region is between the first region and the third region; a first contact region of the first conductivity type and a second contact region of the second conductivity type located in the first region having the first conductivity type; a third contact region of the first conductivity type and a fourth contact region of the second conductivity type located in the second region having the second conductivity type; a fifth contact region of the first conductivity type and a sixth contact region of the second conductivity type located in the third region having the first conductivity type; and a blocking region having a higher resistivity than the region having the second conductivity type, wherein the blocking region is located between the third contact region of the first conductivity type and the fourth contact region of the second conductivity type in the second region having the second conductivity type, for reducing a trigger voltage of the silicon controlled rectifier.
An integrated circuit includes an electrostatic discharge (ESD) protection device containing a silicon controlled rectifier (SCR) built on a semiconductor substrate. The SCR has alternating regions of different conductivity types (N-type and P-type): a first region (N or P), a second region (opposite type to the first), and a third region (same type as the first). Contact regions are present in each of these regions to allow electrical connections. Crucially, a high-resistivity "blocking region" is placed within the second region (between two contact regions) to reduce the voltage needed to trigger the SCR, enhancing its ESD protection.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 9, 2016
July 11, 2017
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